Obstructive sleep apnea (OSA) is highly prevalent, affecting one in five adults in the United States. One in fifteen adults has moderate to severe OSA requiring treatment. Untreated OSA results in reduced quality of life measures and increased risk of disease including hypertension, stroke, heart disease, etc.
Continuous positive airway pressure (CPAP) is a standard treatment for OSA. While CPAP is non-invasive and highly effective, it is not well tolerated by patients. Patient compliance for CPAP is often reported to be between 40% and 60%.
Surgical treatment options for OSA are available too. However, they tend to be highly invasive (result in structural changes), irreversible, and have poor and/or inconsistent efficacy. Even the more effective surgical procedures are undesirable because they usually require multiple invasive and irreversible operations, they may alter a patient's appearance (e.g., maxillo-mandibulary advancement), and/or they may be socially stigmatic (e.g., tracheostomy).
U.S. Pat. No. 4,830,008 to Meer proposes hypoglossal nerve stimulation as an alternative treatment for OSA. An example of an implanted hypoglossal nerve stimulator for OSA treatment is the Inspire™ technology developed by Medtronic, Inc. (Fridley, Minn.). The Inspire device is not FDA approved and is not for commercial sale. The Inspire device includes an implanted neurostimulator, an implanted nerve cuff electrode connected to the neurostimulator by a lead, and an implanted intra-thoracic pressure sensor for respiratory feedback, stimulus trigger, and/or timing of stimulus delivery. The Inspire device was shown to be efficacious (approximately 75% response rate as defined by a 50% or more reduction in RDI (Respiratory Disturbance Index) and a post RDI of .ltoreq.20) in an eight patient human clinical study, the results of which were published by Schwartz et al. and Eisele et al. However, both authors reported that only three of eight patients remained free from device malfunction, thus demonstrating the need for improvements.
Hypoglossal nerve stimulation has been proposed for the treatment of obstructive sleep apnea. An example of an implantable hypoglossal nerve stimulation system is described in U.S. Pat. No. 7,809,442 to Bolea et al. Published data suggest that response to hypoglossal nerve stimulation varies across subjects. Before undergoing a surgical procedure to implant a hypoglossal nerve stimulation system, it would be desirable to understand the likelihood of therapeutic success, and make clinical judgments accordingly. It would also be desirable to consider adjunct therapies to hypoglossal nerve stimulation to improve outcomes thereof.